mirror of
https://github.com/erangell/A2NoSlotMIDI.git
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266 lines
10 KiB
ArmAsm
266 lines
10 KiB
ArmAsm
;-------------------------------------------------------------------------
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;
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; main.s
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; A2NoSlotMidi
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;
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; Created by Eric Rangell on 7/17/18.
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;-------------------------------------------------------------------------
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; APPLE MIDI DRIVER THROUGH ANNUNCIATOR 0
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; Copyright © 1998-2018 Eric Rangell. MIT License.
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;-------------------------------------------------------------------------
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; THIS DRIVER IMPLEMENTS ASYNCHRONOUS SERIAL DATA TRANSMISSION
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; THROUGH THE APPLE ANNUNCIATOR 0 OUTPUT PORT OF THE GAME CONNECTOR
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; USING 32 CYCLES PER BIT TO ACHIEVE A 31.25K MIDI BAUD RATE.
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;
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; THE OUTPUT IS INITIALIZED TO A HIGH LOGIC VOLTAGE. WHEN IT GOES
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; LOW FOR 32 MICROSECONDS, THAT INDICATES THE START BIT OF A MIDI BYTE.
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; THEN 8 BYTES OF DATA ARE TRANSMITTED, FOLLOWED BY A HIGH STOP BIT.
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; THE DATA BYTES REPRESENT MIDI MESSAGES WHICH CAN BE INTERPRETED BY
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; ANY MUSICAL INSTRUMENT THAT IMPLEMENTS MIDI.
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;
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; ENTRY POINTS: (Note: Origin must be set in Makefile)
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;
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; $9000 = INITIALIZE - TURNS ON ANNUNCIATOR 0 - MUST BE CALLED ONCE
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; $9003 = APPLESOFT CALL TO SEND ONE MIDI BYTE. POKE THE BYTE IN $9004.
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; $9005 = ASSEMBLY CALL TO SEND ONE MIDI BYTE FROM ACCUMULATOR
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; $9008 = APPLESOFT OR ASSEMBLY CALL TO SEND SEVERAL BYTES AT ONCE:
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; THE CALLER POPULATES LOCATION $D7 WITH THE NUMBER OF BYTES TO BE
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; TRANSMITTED, AND A POINTER IN $CE,CF (LO,HI) WITH THE ADDRESS OF
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; THE DATA BYTES, THEN CALLS THE ENTRY POINT "SENDMSG" TO TRANSMIT
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; THE MESSAGE.
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; $900B = SEND A TEST MESSAGE - C MAJOR CHORD NOTE ONS
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; $900E = SEND A TEST MESSAGE - C MAJOR CHORD NOTE OFFS
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; $9011 = RESERVED
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; $9014 = RESERVED
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; $9017 = RESERVED
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;-------------------------------------------------------------------------
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; Enhancements for 2018:
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; 1. Disable interrupts during critical timing sections, preserve interrupt status
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; 2. Entry point to reconfigure program to use a different annunciator pair
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; 3. Entry point to reconfigure program for hardware interface using inverters only (not buffers)
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;-------------------------------------------------------------------------
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; CALLER MUST POPULATE THE FOLLOWING TWO ZERO PAGE LOCATIONS FOR SENDMSG:
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NUMBYTES = $D7 ;NUMBER OF BYTES TO BE TRANSMITTED NOW (1-256)
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; ;THE VALUE 0 WILL TRANSMIT 256 BYTES.
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DATAPTR = $CE ;POINTER TO THE BYTES TO BE TRANSMITTED NOW
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;-------------------------------------------------------------------------
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AN0OFF = $C058 ;APPLE ADDRESSES THAT CONTROL ANNUNCIATOR OUTPUTS
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AN0ON = $C059 ;PROGRAM REFERNCES ARE RELATIVE TO AN0
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;AN1OFF = $C05A
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;AN1ON = $C05B
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;AN2OFF = $C05C
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;AN2ON = $C05D
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;AN3OFF = $C05E
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;AN3ON = $C05F
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;-------------------------------------------------------------------------
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.proc main
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;---------------------------------------------------------------------------
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START:
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JMP INIT ;MAIN ENTRY POINT - INITIALIZES ANNUNCIATORS
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SENDFP:
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LDA #$90 ;ENTRY POINT FOR APPLESOFT: POKE BYTE AND CALL
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SENDONE:
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JMP XMITONE ;ENTRY POINT FOR TRANSMITTING ONE BYTE FROM ACCUM
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SENDMSG:
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JMP XMITMSG ;ENTRY POINT FOR TRANSMITTING A MIDI MESSAGE
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ALLNOFF:
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JMP QUIET ;TURN ALL NOTES OFF
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TEST1:
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JMP TESTMSG1 ;SEND TEST MESSAGE 1 - C MAJOR CHORD ON
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TEST2:
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JMP TESTMSG2 ;SEND TEST MESSAGE 2 - C MAJOR CHORD OFF
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;
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;RSRVD1:
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;JMP INIT
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;RSRVD2:
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;JMP INIT
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;RSRVD3:
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;JMP INIT
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;---------------------------------------------------------------------------
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SAVENBYT: .byte $00 ;SAVE AREA FOR NUMBYTES
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TEMPA: .byte $00
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TEMPX: .byte $00
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;ANNPAIR: .byte $00 ; ANNUNCIATOR NUMBER TIMES 2 (1=C05A, 2=C05C, 3=C05E)
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;---------------------------------------------------------------------------
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INIT:
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BIT AN0ON
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RTS
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;---------------------------------------------------------------------------
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XMITMSG:
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LDA NUMBYTES ;SAVE NUMBER OF BYTES
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STA SAVENBYT ;BECAUSE WE WILL CLOBBER IT
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LDY #$00 ;Y WILL BE AN INDEX INTO THE DATA AREA
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XMITLOOP:
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LDA (DATAPTR),Y ;GET A DATA BYTE
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JSR XMITONE
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INY ;POINT TO NEXT BYTE
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DEC NUMBYTES ;DECREMENT COUNTER
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LDA NUMBYTES ;CHECK IF ZERO
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BNE XMITLOOP ;LOOP UNTIL DONE SENDING ALL BYTES
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LDA SAVENBYT
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STA NUMBYTES ;RESTORE ORIGINAL VALUE OF NUMBYTES
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RTS
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;---------------------------------------------------------------------------
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XMITONE:
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STA TEMPA ;SAVE A AND X REGISTERS
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STX TEMPX
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT7+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT6+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT5+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT4+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT3+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT2+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT1+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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ASL A ;SHIFT BIT INTO CARRY
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TAX ;SAVE CURRENT IMAGE OF DATA BYTE
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LDA #$00 ;ZERO OUT ACCUMULATOR FOR ADD
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ADC #<AN0OFF ;ADD CARRY TO ANNUNCIATOR ADDRESS
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STA BIT0+1 ;MODIFY THE XMITBITS SUBROUTINE
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TXA ;RESTORE ACCUMULATOR
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;
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JSR XMITBITS ;SEND THE BYTE OUT
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LDX TEMPX
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LDA TEMPA ;RESTORE X AND A
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RTS
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;-----------------------------------------------------------------------
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XMITBITS:
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BIT AN0OFF ;4 CYCLES - TRANSMIT START BIT - ALWAYS LOW
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JSR DELAY22 ;6+22
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BIT0:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT1:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT2:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT3:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT4:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT5:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT6:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT7:
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BIT AN0OFF ;4
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JSR DELAY22 ;6+22
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BIT AN0ON ;4 ;TRANSMIT STOP BIT - ALWAYS HIGH
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JSR DELAY22 ;6+22
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RTS
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;-----------------------------------------------------------------------
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DELAY22:
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NOP ;WAIT 22 CYCLES
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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NOP
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RTS
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;-----------------------------------------------------------------------
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TESTMSG1:
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LDA #7
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STA NUMBYTES
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LDA #<TESTDAT1
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STA DATAPTR
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LDA #>TESTDAT1
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STA DATAPTR+1
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JSR SENDMSG
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RTS
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;-----------------------------------------------------------------------
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TESTMSG2:
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LDA #7
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STA NUMBYTES
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LDA #<TESTDAT2
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STA DATAPTR
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LDA #>TESTDAT2
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STA DATAPTR+1
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JSR SENDMSG
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RTS
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;-----------------------------------------------------------------------
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QUIET:
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LDA #$90
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STA NUMBYTES
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LDA #<QUIETMSG
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STA DATAPTR
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LDA #>QUIETMSG
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STA DATAPTR+1
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JSR SENDMSG
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RTS
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;-----------------------------------------------------------------------
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TESTDAT1:
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.byte $90,$3C,$40,$40,$40,$43,$40
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TESTDAT2:
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.byte $90,$3C,$00,$40,$00,$43,$00
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QUIETMSG:
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.byte $B0,$78,$00,$B0,$79,$00,$B0,$7B,$00
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.byte $B1,$78,$00,$B1,$79,$00,$B1,$7B,$00
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.byte $B2,$78,$00,$B2,$79,$00,$B2,$7B,$00
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.byte $B3,$78,$00,$B3,$79,$00,$B3,$7B,$00
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.byte $B4,$78,$00,$B4,$79,$00,$B4,$7B,$00
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.byte $B5,$78,$00,$B5,$79,$00,$B5,$7B,$00
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.byte $B6,$78,$00,$B6,$79,$00,$B6,$7B,$00
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.byte $B7,$78,$00,$B7,$79,$00,$B7,$7B,$00
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.byte $B8,$78,$00,$B8,$79,$00,$B8,$7B,$00
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.byte $B9,$78,$00,$B9,$79,$00,$B9,$7B,$00
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.byte $BA,$78,$00,$BA,$79,$00,$BA,$7B,$00
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.byte $BB,$78,$00,$BB,$79,$00,$BB,$7B,$00
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.byte $BC,$78,$00,$BC,$79,$00,$BC,$7B,$00
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.byte $BD,$78,$00,$BD,$79,$00,$BD,$7B,$00
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.byte $BE,$78,$00,$BE,$79,$00,$BE,$7B,$00
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.byte $BF,$78,$00,$BF,$79,$00,$BF,$7B,$00
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;----------------
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; END OF PROGRAM
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;----------------
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.endproc
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